Composite inorganic structures such as ceramics, can be considered as being in the nature of laminates where at least one inorganic structure, such as a zirconia plate, is adhered to another, such as an alumina plate. Such composite ceramics would be of considerable value in the refractory industry if an adequate bond could be obtained between the different ceramics sufficient to withstand the high temperatures and thermal shock to which they are frequently subjected particularly in the metal and glass industries. Prior attempts to produce such composite ceramics by simultaneous firing of the ceramics in a single mold or by firing the ceramics separately and cementing them together have not been successful to applicants' knowledge. The interfacial bonds between the different ceramics obtained in these manners have not been adequate to withstand the high temperatures and thermal shock to which they are frequently subjected. This interfacial bond failure is caused by a number of factors but is mainly due to the differences in the thermal coefficients of expansion of the different refractories or ceramics. A further problem involved in producing composite ceramics is the difference in the firing temperatures required of the different ceramic materials.
Freezing a slurry of ceramic material to form ceramic structures has been disclosed in the U.S. Pat. Nos. 3,177,161; 3,512,571; 3,816,572 and 3,885,005. None of these patents, however, disclose or suggest the formation of composite ceramic articles of different ceramic materials.